The Hearthware Precision roaster is both a marvel and a flop.
It is a marvel because it provides a very simple introduction to roasting coffee at home, and because it produces a good, if somewhat bright, product. The quality of the roasted coffee can't be overlooked -- people are amazed that one can roast such great coffee at home so simply. If mine had not failed, I would probably still be using it today, despite the disadvantages of its small 1/2 cup capacity and its consistently bright product. Too bright is much better than too old!
It is a flop because a few flaws in the design made many of the units fail far too early. In a survey I conducted on alt.coffee in 2001, nearly 1/3 of the survey respondents reported that their Precisions had failed due to fan motor breakdowns.
The basic design is ingenious. Green coffee is added to a cylindrical glass roasting chamber with a shallow inverted steel cone-shaped bottom and a removable lid. Hot air is blown into the roasting chamber through a grid at the bottom apex of the cone. The source of the hot air is a plastic cylindrical base that contains a heater, fan, and controls.
As the beans are dried by the hot air they become light enough to be circulated by the hot air flowing up from the base. As the roast progresses the skin of the bean peels off and is carried up to the top of the roasting chamber, where most of it is captured by a simple but remarkably effective and neat chaff catcher built into the lid.
Using the Hearthware is about as simple as coffee roasting gets. You simply measure your beans with a ½ cup scoop provided by Hearthware and dump it into the roasting chamber. The chamber locks loosely onto the base with a bayonet fastener. Arrows cast into the plastic base help the user to align the base and the roasting chamber to the bayonet tabs. The lid of the roasting chamber locks onto the top of the roasting chamber with a similar fastener.
The degree of doneness is set by a single graduated dial with numbers ranging from 1 to 10. No units are specified, and the numbers do not correspond to roasting time. Once the machine is plugged in to a standard 110V outlet the roast is started by turning the dial to the desired roast setting and pressing the roast button. Learning which setting to use is a matter of trial and error. I found that most beans roast to mid-way into second crack at a setting of "6". More about achieving the desired degree of doneness later.
The Precision is noisy. It sounds a little like the motor of those model airplanes powered by tiny butane-fueled piston engines. It begins heating the beans to operating temperature, and when it is reached, the heating element cycles on and off to maintain the temperature within a programmed range. As the heater cycles the fan motor speeds and slows, giving the Precision its characteristic high-low-high whine. As the beans begin to heat and dry they give off a sweet, grassy odour. This changes gradually as the roast progresses, transitioning through a pleasant roasted coffee smell and finally into an offensive, acrid burning-tire smell as second crack is reached.
A red indicator light signals that the machine is in roasting mode. When the beans have reached the doneness corresponding to the roast setting the red light goes out, a green light comes on, and the machine shifts automatically into the cooling cycle. This shuts the heater off while the fan in the base continues to circulate unheated air through the roasting chamber, cooling the beans to near room temperature in approximately 4 minutes.
The beans emit a lot of smoke as the roast progresses. While some people don't seem to mind roasting indoors, I hated it! I did my first roast in my basement bathroom because it had a very efficient fan that created a negative pressure in the bathroom. I thought it would function like a fume hood, and no smell would escape into the rest of the house. How wrong I was! Our house smelled of coffee smoke for 36 hours, and the basement bathroom still reeked 3 days later. Up to 7 days later I could still smell coffee if I wiped my finger on the bathroom walls or mirror.
After this inauspicious start I roasted outdoors, summer and winter. During the first outdoor roast our elderly Chinese neighbour lady came running over with a fire extinguisher, thinking our house was going up in flames. This led me to coin a new phrase -- where there is smoke, there's a Precision. Ambient outdoor temperatures required some adjustment of roasting times, but I found the Precision could still produce and acceptable roast year-round, from 28C to at -4C.
Gauging the degree of roast is relatively simple. Coffee beans go through a series of characteristic "cracks" as they roast. The loud, sharp "first crack" is plainly audible from 15 feet away; the gentle "snap" of second crack is more muted, but easily distinguished from first crack. With a little experience my roasting process evolved into simply setting the Hearthware at 7 or more, letting the roast roll into second crack, then to pushing the "cool" button to stop the heater and force the Precision into cooling mode. I got very consistent roast quality by timing from the start of second crack, then stopping the roast after intervals established by the taste I preferred from each of the blends I used regularly.
No-one recommends leaving the Precision unattended during roasting for obvious reasons. But I began to do just that. I would set the dial at "6", leave the Precision running under our back porch, monitoring the roasting progress by the sound of the motor which I could hear clearly from inside the house. A continuous high pitched whine indicates that the heater has stopped cycling on and off, and the cooling cycle has begun. (This is the part where you expect me to write about the unattended roaster catching on fire, but I never had a mishap with the Precision.)
I had to roast at least 5 batches per week to keep myself in coffee, and that wears after a while. I wished many times that Hearthware would develop a new, improved, larger roaster with the same ease of operation. (They have done so with their I-roast.) Running two roasts back to back is not recommended without a cool-down period, and I usually obeyed the cool down rule. But it took me approximately 30 minutes, including all setup and cleanup, to roast 170 grams of beans, which I had to do every 3 days.
I liked the roasts from the Hearthware for espresso but found them too bright for other brewing methods. I found that certain beans tasted great from the Hearthware -- I especially liked the deeper, richer tasting beans. But I found that some beans such as Columbian, Peru and Kona came out too bright for my taste. (I have a renewed appreciation for these beans now that I'm using a different roasting method.)
After approximately 1 year I began reading reports that other Precision owners were losing their machines to the failure of a fan bearing. When the bearing on my machine became noisy I decided to disassemble my machine and to see what could be done to modify it for longer life. I made a few modifications, then drilled a hole in the base of the machine through which to oil the bottom fan motor bearing to extend its life. I kept the Precision running for 2 more years by oiling the bearing before every roast. Finally it seized up during a roast. By this time I no longer "set and forget" my roasts, and I was standing by to turn it off when the bearing failed in mid-roast.
For the past 6 months I have been roasting with an Infinity Convection oven roaster set on top of a Stir Crazy popcorn popper base with the heating element disconnected. This combination roasts 350 grams of green in 30 minutes from start of setup to completion of final cleanup. It is almost the antithesis of the Precision, producing deep, earthy flavours, but a little short on brightness. It is not quite as convenient to use as the Precision, but it is still easy, and I can get by roasting only once per week. Like the Precision it is strictly an outside roaster, but it is a big improvement over the Precision.